1. Field of the Invention
This invention relates to a method and apparatus for testing an optical transceiver. In particular, method and apparatus are disclosed for providing a self-test feature for an apparatus utilizing an infrared communication link, such as commercial laundry appliances having data acquisition systems for storing information on appliance usage for subsequent transmission to a portable data unit.
2. Description of the Prior Art
Wireless communication utilizing optical signals is used in a variety of applications today. For example, infrared communication links may be provided between data accumulation devices and portable data units. In the commercial laundry field, coin operated laundry appliances are now provided with systems for accumulating information regarding operation of the appliance for subsequent retrieval by portable data units, such as handheld computers with cooperating optical transceivers. Use of wireless optical communication avoids problems inherent in any physical electrical connection (such as plug access and contamination) or radio frequency communication (such as interference and government regulation). Examples of such systems are provided by e.g. U.S. Pat. Nos. 4,306,219 (Main et al.); 4,369,442 (Werth et al.); and 4,845,484 (Ellsberg).
It is desirable to provide the optical communication system utilized in these systems with two-way communication capability, whereby the appliance may both transmit information to a portable collection unit and receive data or programming from a portable data unit. The appliance is therefore provided with both means for generating and transmitting optical signals, and means for receiving optical signals transmitted by an external device. Both an optical emitter and an optical detector are provided. Appropriate transmitting circuitry is provided for receiving signals for transmission and energizing the emitter to generate corresponding coded optical signals, and receiving circuitry is provided for discriminating detected optical signals into output electrical signals for further processing by the appliance. As discussed in the Ellsberg '484 patent, the optical emitters and detectors have preferably been arranged so that the radiation transmitted by the optical emitter, typically in a conical beam, will not be read by the optical detector of that transceiver.
A failure in any of the foregoing elements may result in an overall failure of the desired communication. For example, a fault in either the transmitting circuitry or the optical emitter may prevent the appliance from transmitting data to a portable data unit, while a fault in either the detector or the receiving circuitry may result in a failure of the appliance to receive information from a portable data unit. Such faults may occur as a result of manufacturing or assembly errors, or may develop due to component deterioration or failure over time during operation.
It is generally desirable to minimize or eliminate the number of faulty components which are incorporated into a new appliance to assure reliable operation in the field. While techniques exist for testing each element of an optical transceiver, such techniques are generally labor intensive and require specialized equipment. Although extensive testing of this type does result in higher reliability and can eliminate faulty systems, the costs are significant and are often excessive. Further, once the components are installed it becomes difficult to access them for future testing, particularly where environmental sealants or "potting" are employed to protect the underlying electronic components. Finally, it is generally not possible or economical to repetitively test each of these elements once the device is in operation, to detect deterioration or failure in the field.